The present invention relates to sender authentication for email, and more particularly, is directed to highly reliable sender authentication for email that is difficult to classify via conventional probabilistic filtering.
Unsolicited commercial email, commonly referred to as spam, is an ever-increasing problem. Email service providers are constantly battling spammers, deploying ever more sophisticated schemes for blocking known spam. In turn, spammers keep using more sophisticated message creation techniques, to avoid being blocked.
With present spam fighting schemes, there is still a portion of email traffic that cannot be definitively determined to be spam or definitively determined to be ham, that is, non-spam. Accordingly, there is a need for an improved way to process the email that is difficult to classify as spam or ham.